Examples of processes of manufacturing a film structural member provided with metal wiring on a transparent substrate include a process of providing a blackened layer on the metal wiring for improving visibility of a film.
The process of providing the blackened layer on the metal wiring will be described with reference to FIG. 8. In FIG. 8, metal layers 4 are provided on transparent substrate 2, blackened assistance layer 6 is provided on metal layer 4, and blackened layer 5 is provided on blackened assistance layer 6. In this manner, by providing blackened layer 5 on metal layer 4 of transparent substrate 2, reflectance of metal layer 4 is reduced. Therefore, the visibility improves. Such a method is described in Japanese Patent Unexamined Publication No. 2015-103223 in detail.
However, in the method of providing the blackened layer on the metal wiring according to an example of the related art, there is a disadvantage that breaking of wiring occurs when the transparent substrate is bent. More specifically, since toughness of copper nitride that is the blackened layer is low, when the transparent substrate is bent, even the metal wiring under the blackened layer is broken due to the breakage of the blackened layer. Therefore, the bending of the transparent substrate is strictly disallowed.